Spin head, chuck pin used in the spin head, and method for treating a substrate with the spin head

ABSTRACT

Provided is a spin head for supporting a substrate. The spin head includes a rotatable body, and chuck pins protruding upward from the body and configured to support an edge of a substrate placed at the body when the body is rotated. Each of the chuck pins includes a vertical rod vertically disposed at the body, and a support rod extending from a side of the vertical rod and configured to make contact with the edge of the substrate placed at the body when the body is rotated. When the substrate is rotated, the vertical rod is spaced apart from the edge of the substrate. The contact portion includes a streamlined side surface. The support rod includes a contact portion. The contact portion tapers toward the end of the support rod when viewed from the top of the support rod.

CROSS-REFERENCE TO RELATED APPLICATIONS

This U.S. non-provisional patent application claims priority under 35U.S.C. § 119 of Korean Patent Application No. 10-2007-0101075, filed onOct. 8, 2007, the entire contents of which are hereby incorporated byreference.

BACKGROUND OF THE INVENTION

The present invention disclosed herein relates to an apparatus fortreating a substrate, and more particularly, to a rotatable spin headconfigured to support a substrate, for example, in a semiconductorprocess, and a method for treating a substrate using the spin head.

Semiconductor processes include a process of etching or cleaning thinlayers, foreign substances, and particles. Such an etching or cleaningprocess may be performed by placing a substrate such as a wafer on aspin head with a patterned side of the wafer facing upward or downwardand supplying a process liquid to the wafer while rotating the spinhead. The spin head includes chuck pins to support the edge of the waferfor preventing the wafer from being detached from the spin head in aradial direction. The chuck pins can be moved between rest positions andsupporting positions. When the chuck pins are in the rest positions, aloading/unloading space is formed on the spin head for loading andunloading a substrate. When a substrate loaded on the spin head istreated while rotating the spin head, the chuck pins are in supportingpositions where the chuck pins make contact with the edge of thesubstrate and support the substrate.

FIG. 23 illustrates a typical spin head 900. The spin head 900 includesa rotatable body 920, support pins 960 configured to support a bottomsurface of a substrate (W), and chuck pins 940 configured to support theedge of the substrate (W). Each of the chuck pins 940 includes arotatable vertical rod 942 and a support rod 944 protruding upward fromthe vertical rod 942. The support rod 944 and the vertical rod 942 areeccentric. A process liquid is supplied to a front center portion of thesubstrate (W), and gas is supplied to the bottom surface of thesubstrate (W) to prevent the process liquid from reaching apredetermined region of the bottom surface of the substrate (W).

FIG. 24 is a top view for explaining disadvantages of chuck pins such asthe chuck pins 940 of FIG. 23. The vertical rods 942 are disposed closeto the substrate (W), and the support rods 944 have a circular shape.Therefore, when the substrate (W) is rotated, streams flowing from thefront center portion of the substrate (W) are largely separated at thesupport rods 944. That is, a process liquid is not smoothly supplied toregions of the substrate (W) close to the support rods 944.

FIG. 25 is a bottom view of the substrate (W) for explainingdisadvantages of support pins such as the support pins 960 of FIG. 23.In the case where the support pins 960 are disposed between thesubstrate (W) and the rotatable body 920 as shown in FIG. 23, streams ofgas supplied to a bottom surface of the substrate (W) are separated atthe support pins 960. Therefore, gas is not sufficiently supplied toregions of the bottom surface of the substrate (W) close to the supportpins 960, and thus a process liquid can permeate between the substrate(W) and the rotatable body 920 past the support pins 960. As a result,an edge portion of the bottom surface of the substrate (W) may benon-uniformly treated. In addition, since the vertical rods 942 of thechuck pins 940 impede streams of gas supplied to the bottom surface ofthe substrate (W), a process liquid can permeate between the substrate(W) and the rotatable body 920 past the vertical rods 942.

In general, the support rods 944 are moved together from rest positionsto supporting positions by a single driving mechanism. Therefore, if thesupport rods 944 are not uniform in size due to machining tolerances,some of the support rods 944 may not be brought into contact with theedge of the substrate (W) although all the support rods 944 are movedtogether to the supporting positions. Thus, the substrate (W) may beunstably supported, and the other chuck pins making contact with theedge of the substrate (W) may be easily damaged due to concentration ofstress.

In addition, if the spin head 900 is rotated at high speed, since astrong centrifugal force is applied to the support rods 944 in adirection from the supporting positions to the rest positions, thesubstrate (W) may be unstably supported.

SUMMARY OF THE INVENTION

The present invention provides a spin head configured to uniformlysupply a process liquid to the top surface of a substrate, and a methodfor treating a substrate using the spin head.

The present invention also provides a spin head configured to uniformlytreat a bottom edge region of a substrate using a cleaning liquid thatis directed to the bottom surface of the substrate after being used totreat the top surface of the substrate, and a method for treating asubstrate using the spin head.

The present invention also provides a spin head having a structure forstably keeping all chuck pins in contact with a substrate.

The present invention also provides a spin head having a structure forstably keeping all chuck pins in contact with an edge portion of asubstrate at high speed.

Objects of the present invention are not limited to those mentionedabove, and other objects of the present invention will be apparentlyunderstood by those skilled in the art through the followingdescription.

Embodiments of the present invention provide spin heads for supporting asubstrate. The spin head include a rotatable body, and chuck pinsprotruding upward from the body and configured to support an edge of asubstrate placed at the body when the body is rotated. Each of the chuckpins includes a vertical rod vertically disposed at the body, and asupport rod extending from a side of the vertical rod and configured tomake contact with the edge of the substrate placed at the body when thebody is rotated.

In some embodiments, the support rod may include a contact portionextending to an end of the support rod and tapering toward the end ofthe support rod when viewed from a top of the support rod. The contactportion may include a rounded side surface in a length direction of thesupport rod. The contact portion may include a streamlined side surfacein a length direction of the support rod. The support rod may have auniform height from a top surface of the body in a length direction ofthe support rod. The support rod may include a distal end that is viewedas a point when viewed from the top of the support rod.

In other embodiments, the support rod may include a horizontal rodextending laterally from the vertical rod, and a contact rod bentdownward from an end of the horizontal rod. The contact rod may have thesame cross section along a length of the contact rod. The contact rodmay taper away from the vertical rod. The contact rod may include astreamlined side surface. The vertical rod may have a circular section,and the contact rod may have a width smaller than a diameter of thecircular section of the vertical rod when viewed from a top of thecontact rod.

In still other embodiments, the spin head may further include a chuckpin moving unit configured to move the chuck pins in radial directionsof the body. The chuck pin moving unit may include: movable rods fixedto the chuck pins; a rotatable cam including protrusions on an outersurface thereof so as to move the chuck pins away from a center of thebody; and chuck pin return units applying forces to the movable rods,respectively, so as to individually move the chuck pins toward thecenter of the body.

In even other embodiments, the chuck pin moving unit may further includecontact maintaining members configured to push the chuck pins toward thecenter of the body when the body is rotated so as to prevent the chuckpins from moving away from the center of the body by a centrifugalforce.

In yet other embodiments, the body may include a lower nozzle memberthrough which gas is injected so as to space the substrate apart fromthe body. The lower nozzle member may include an injection hole formedin a top surface of the body into a circular shape. The lower nozzlemember may further include: a passage portion connected to a gas supplyconduit and having the same cross section along a length thereof; and aninjection portion extending upward from the passage portion andconnected to the injection hole, the injection portion having agradually increasing cross section along an upward direction.

In other embodiments of the present invention, there are provided chuckpins used in a rotatable spin head for supporting an edge of asubstrate. The chuck pins include a vertical rod disposed in a verticaldirection, and a support rod extending from a side of the vertical rod.

In some embodiments, the support rod may include a contact portionextending to an end of the support rod in a tapered shape. The contactportion may include a rounded side surface in a length direction of thesupport rod. The contact portion may include a streamlined side surface.The support rod may have a uniform height in a length direction thereof.

In other embodiments, the support rod may include a horizontal rodextending laterally from the vertical rod, and a contact rod bentdownward from an end of the horizontal rod. The contact rod may taperaway from the vertical rod. The contact rod may have the same crosssection along a length of the contact rod. The contact rod may include astreamlined side surface.

In still other embodiments of the present invention, there are providedmethods for treating a substrate. The methods include supporting asubstrate placed at a body of a spin head by brining chuck pins intocontact with an edge of the substrate, wherein each of the chuck pinsincludes a vertical rod vertically disposed at the body and a supportrod extending from a side of the vertical rod, wherein when the chuckpin supports the substrate, the vertical rod is spaced apart from thesubstrate in a lateral direction, and a distal end of the support rod isbrought into contact with the edge of the substrate.

In some embodiments, the support rod may include a contact portionextending to an end of the support rod in a tapered shape when viewedfrom a top of the support rod, and the contact portion may behorizontally disposed at the same height as the substrate placed at thespin head.

In other embodiments, the support rod may include a horizontal rodextending laterally from the vertical rod, and a contact rod bentdownward from an end of the horizontal rod, wherein the horizontal rodis horizontally disposed higher than the substrate placed at the spinhead, and the contact rod extends downward to a level of the substrateplaced at the spin head or lower than the level of the substrate placedat the spin head. The contact rod may taper away from the vertical rodwhen viewed form a top of the contact rod. The contact rod may have thesame cross section along a length thereof.

In still other embodiments, the substrate may be placed at the spin headwith a patterned side of the substrate facing downward, and a processliquid may be supplied to a top center portion of the substrate when thespin head is rotated.

In even other embodiments, the substrate may be spaced a predetermineddistance from the spin head by a pressure of gas injected upward fromthe spin head.

BRIEF DESCRIPTION OF THE FIGURES

The accompanying figures are included to provide a further understandingof the present invention, and are incorporated in and constitute a partof this specification. The drawings illustrate exemplary embodiments ofthe present invention and, together with the description, serve toexplain principles of the present invention. In the figures:

FIG. 1 is a schematic plan view illustrating a substrate treatingapparatus according to an embodiment of the present invention;

FIG. 2 is a cross-sectional view illustrating a container according toan embodiment of the present invention;

FIG. 3 is a vertical cut-away view of the contained of FIG. 2, accordingto an embodiment of the present invention;

FIG. 4 is a plan view illustrating a spin head according to anembodiment of the present invention;

FIG. 5 is a sectional view of the spin head taken along line I-I of FIG.4, according to an embodiment of the present invention;

FIG. 6 is a perspective view illustrating a chuck pin according to anembodiment of the present invention;

FIG. 7 is a perspective view illustrating a modified version of thechuck pin of FIG. 6, according to another embodiment of the presentinvention;

FIG. 8 is a view illustrating how the chuck pin of FIG. 6 supports theedge of a substrate according to an embodiment of the present invention;

FIG. 9 is a view illustrating streams flowing on a rotating substrateaccording to an embodiment of the present invention;

FIG. 10 is a perspective view illustrating a chuck pin according toanother embodiment of the present invention;

FIG. 11 is a view illustrating how the chuck pin of FIG. 10 supports theedge of a substrate according to an embodiment of the present invention;

FIG. 12 is a view illustrating a substrate supported by a body, streamsof a process liquid supplied through an upper nozzle member, and streamsof gas supplied through a lower nozzle member according to an embodimentof the present invention;

FIG. 13 is a sectional view of the spin head taken along line II-II ofFIG. 4, according to an embodiment of the present invention;

FIG. 14 is a partial view illustrating a lower plate in the direction ofarrow A in FIG. 6, according to an embodiment of the present invention;

FIG. 15 is a view for illustrating a relationship between the lowerplate and an upper plate when the upper plate expands, according to anembodiment of the present invention;

FIG. 16 is a bottom view illustrating a chuck pin moving unit disposedon the bottom of the lower plate, according to an embodiment of thepresent invention;

FIG. 17 is an enlarged view of portion B of FIG. 16, according to anembodiment of the present invention;

FIG. 18 is a view illustrating another example of a cam return unit ofFIG. 17, according to another embodiment of the present invention;

FIG. 19 is a view illustrating another example of a chum pin return unitof FIG. 17, according to another embodiment of the present invention;

FIGS. 20A and 20B are views illustrating forces exerted by components ofthe chuck pin moving unit and moving directions of the components of thechuck pin moving unit when a chuck pin is shifted between a restposition and a supporting position by the chuck pin moving unit,according to an embodiment of the present invention;

FIG. 21 is a view illustrating how a contact maintaining unit keeps thechuck pin in contact with a substrate using a centrifugal forceaccording to an embodiment of the present invention;

FIG. 22 is a view illustrating how the supporting position of the chuckpin is changed by moving an adjustment block according to an embodimentof the present invention;

FIG. 23 is a schematic view illustrating a typical spin head;

FIG. 24 is a view for explaining disadvantages of chuck pins such asthose depicted in FIG. 23; and

FIG. 25 is a view for explaining disadvantages of support pins such asthose depicted in FIG. 23.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Preferred embodiments of the present invention will be described belowin more detail with reference to FIGS. 1 through 22. The presentinvention may, however, be embodied in different forms and should not beconstrued as limited to the embodiments set forth herein. Rather, theseembodiments are provided so that this disclosure will be thorough andcomplete, and will fully convey the scope of the present invention tothose skilled in the art.

In the following descriptions of embodiments, an apparatus for cleaninga substrate (W) using a chemical, a rinsing liquid, and a dry gas isdescribed as an example. That is, the spirit and scope of the presentinvention is not limited to the exemplary substrate cleaning apparatus.The present invention can be applied to various apparatuses such as anetching apparatus that processes a substrate while rotating thesubstrate.

FIG. 1 is a schematic plan view illustrating a substrate treatingapparatus 1 according to an embodiment of the present invention.Referring to FIG. 1, the substrate treating apparatus 1 includes a fluidsupply unit 10, a container 20, a lifting unit 30, and a spin head 40.The fluid supply unit 10 supplies a process liquid or gas to a substrate(W) for treating the substrate (W). The spin head 40 supports androtates the substrate (W) during a process. The substrate (W) is placedat the spin head 40 with a patterned side of the substrate (W) facingdownward. Alternatively, the substrate (W) may be placed at the spinhead 40 with a patterned side of the substrate (W) facing upward. Thecontainer 20 prevents process chemicals and waste fumes from splashingout or leaking out. The lifting unit 30 is used to move the spin head 40or the container 20 in a vertical direction so as to adjust the relativeheight between the container 20 and the spin head 40.

The fluid supply unit 10 includes an upper nozzle member 100 a and alower nozzle member 100 b. The upper nozzle member 100 a supplies aprocess liquid or a process gas to a top center portion of a substrate(W) placed at the spin head 40, and the lower nozzle member 100 bsupplies gas to a bottom surface of the substrate (W). The substrate (W)is spaced a predetermined distance apart from a top surface of the spinhead 40. The lower nozzle member 100 b supplies gas to a gap between thesubstrate (W) and the spin head 40. The gas may be nitrogen gas.Alternatively, the gas may be an inert gas or clean air. The processliquid or process gas supplied through the upper nozzle member 100 a tothe top center portion of the substrate (W) is spread toward the edge ofthe substrate (W) by a centrifugal force. Then, the process liquid orprocess gas flows toward a bottom surface region of the substrate (W).Gas is supplied to a center portion of the bottom surface of thesubstrate (W) through the lower nozzle member 100 b so as to prevent theprocess liquid or process gas from reaching a predetermined region ofthe bottom surface of the substrate (W). Therefore, the entire topsurface of the substrate (W) and a bottom edge portion of the substrate(W) are treated by the process liquid or the process gas. The substrate(W) is spaced a predetermined distance from the spin head 40 by thepressure of gas supplied through the lower nozzle member 100 b. Thesubstrate (W) is placed at the spin head 40 with the bottom surface ofthe substrate (W) being spaced apart from the spin head 40.

The upper nozzle member 100 a includes a chemical supply nozzle 120 a, arinsing liquid supply nozzle 140 a, and a dry gas supply nozzle 160 a.The chemical supply nozzle 120 a supplies a plurality of chemicals tothe substrate (W). The chemical supply nozzle 120 a includes a pluralityof injectors 121, a support bar 122, and a bar mover 125. The injectors121 are disposed at a side of the container 20. The injectors 121 arerespectively connected to chemical tanks (not shown) for receivingchemicals from the chemical tanks. The chemical tanks connected to theinjectors 121 store different chemicals. The injectors 121 are arrangedin a predetermined direction in parallel with each other. The injectors121 include upward protrusions 121 a, respectively. Grooves (not shown)may be formed in side portions of the protrusions 121 a, respectively.The chemical may be sulfuric acid, nitric acid, ammonia, hydrofluoricacid, or a mixture of deionized water and one or more of the listedchemicals. A discharge hole is formed in an end of each of the injectors121.

The support bar 122 is coupled to one of the injectors 121 for movingthe injectors 121 above the substrate (W) placed on the spin head 40.The support bar 122 is shaped like a long rod and is disposed in amanner such that the length of the support bar 122 is perpendicular tothe arranged direction of the injectors 121. A holder (not shown) isattached to a bottom surface of the support bar 122 for coupling thesupport bar 122 and the injectors 121. The holder includes arms (notshown), and the arms are insertable into the grooves formed in theprotrusions 121 a of the injectors 121. The arms may be rotatable ormovable into the grooves.

The bar mover 125 moves the support bar 122 along a linear path betweena position above the support bar 122 and a position above the substrate(W) placed on the spin head 40. The bar mover 125 includes a bracket123, a guide rail 124, and a driving unit (not shown). The guide rail124 extends straight along the injectors 121 and the container 20 fromthe outside of the injectors 121 to the outside of the container 20. Thebracket 123 is coupled to the guide rail 124 and is movable on the guiderail 124. The support bar 122 is fixed to the bracket 123. The drivingunit provides a driving force for moving the bracket 123 linearly. Thebracket 123 may be linearly moved using a motor and a screw.Alternatively, the bracket 123 may be linearly moved using a belt, apulley, and a motor. Alternatively, the bracket 123 may be linearlymoved using a linear motor.

The rinsing liquid supply nozzle 140 a is disposed at another side ofthe container 20, and the dry gas supply nozzle 160 a is disposed atanother side of the container 20. The rinsing liquid supply nozzle 140 aincludes an injector 141, a support bar 142, and a driving unit 144. Theinjector 141 is fixed to an end of the support bar 142. A rotation shaft(not shown) is fixed to the other end of the support bar 142, and thedriving unit 144 rotates the rotation shaft. The injector 141 receives arinsing liquid from a rinsing liquid tank (not shown). The dry gassupply nozzle 160 a has a structure similar to that of the rinsingliquid supply nozzle 140 a. The dry gas supply nozzle 160 a is used tosupply isopropyl alcohol and nitrogen gas. The nitrogen gas may besupplied through the dry gas supply nozzle 160 a at a high temperature.The lower nozzle member 100 b will be described later in detail.

FIG. 2 is a cross-sectional view illustrating the container 20 accordingto an embodiment of the present invention, and FIG. 3 is a verticalcut-away view illustrating the contained 20 according to an embodimentof the present invention. Referring to FIGS. 2 and 3, the container 20has a space 32 with an opened top, and the spin head 40 is disposed inthe space 32 for treating a substrate (W). A rotation shaft 42 is fixedto a bottom surface of the spin head 40 for supporting and rotating thespin head 40. The rotation shaft 42 is inserted through an openingformed through a bottom surface of the container 20 and protrudesoutward from the container 20. A driving unit 44 such as a motor isfixedly coupled to the rotation shaft 42 for rotating the rotation shaft42.

FIG. 3 is a cut-away view illustrating the inside structure of thecontainer 20. Referring to FIGS. 2 and 3, the container 20 is configuredto collect chemicals separately after the chemicals are used fortreating the substrate (W). Thus, the chemicals can be reused. Thecontainer 20 includes a plurality of collecting vessels 220, 240, and260. Process liquids are separately collected to the collecting vessels220, 240, and 260 after the process liquids are used. In the currentembodiment, the container 20 includes three collecting vessels 220, 240,and 260. Hereinafter, the three collecting vessels 220, 240, and 260will be also referred as an inner collecting vessel, a middle collectingvessel, and an outer collecting vessel, respectively.

The inner collecting vessel 220 is shaped like a ring for enclosing thespin head 40. The middle collecting vessel 240 is shaped like a ring forenclosing the inner collecting vessel 220. The outer collecting vessel260 is shaped like a ring for enclosing the middle collecting vessel240. The collecting vessels 220, 240, and 260 include inlets 227, 247,and 267, respectively. The inlets 227, 247, and 267 communicate with thespace 32 of the container 20. Each of the inlets 227, 247, and 267 isshaped like a ring enclosing the spin head 40. Chemicals injected to thesubstrate (W) are directed to the inlets 227, 247, and 267 by acentrifugal force generated by rotation of the substrate (W) and thenare collected to the collecting vessels 220, 240, and 260. The inlet 267of the outer collecting vessel 260 is located above the inlet 247 of themiddle collecting vessel 240, and the inlet 247 of the middle collectingvessel 240 is located just above the inlet 227 of the inner collectingvessel 220. That is, the inlets 227, 247, and 267 of the inner, middle,and outer collecting vessels 220, 240, and 260 are disposed at differentheights.

The inner collecting vessel 220 includes an outer wall 222, a bottomwall 224, an inner wall 226, and a guide wall 228. Each of the outerwall 222, the bottom wall 224, the inner wall 226, and the guide wall228 is shaped like a ring. The outer wall 222 includes an oblique wall222 a and a vertical wall 222 b. The oblique wall 222 a is sloped downin a direction away from the spin head 40. The vertical wall 222 bextends downward from the oblique wall 222 a. The bottom wall 224extends horizontally from a lower edge of the vertical wall 222 b towardthe spin head 40. An end of the bottom wall 224 is aligned with a topend of the oblique wall 222 a. The inner wall 226 extends verticallyupwardly from the end of the bottom wall 224. A top end of the innerwall 226 is spaced a predetermined distance from the top end of theoblique wall 222 a. A gap between the vertically space inner wall 226and the oblique wall 222 a functions as the inlet 227.

A plurality of holes 223 are formed in the inner wall 226 in a circularfashion. Each of the holes 223 is shaped like a slit. The holes 223functions as exhaust holes. That is, gases introduced into the innercollecting vessel 220 are discharged to the outside of the container 20through the exhaust holes 223 and a space under the spin head 40. Adischarge pipe 225 is coupled to the bottom wall 224. A used processliquid collected into the inner collecting vessel 220 is discharged toan outer recycle system through the discharge pipe 225.

The guide wall 228 includes an oblique wall 228 a and a vertical wall228 b. The oblique wall 228 a is sloped down from a top end portion ofthe inner wall 226 in a direction away from the spin head 40. Thevertical wall 228 b extends vertically downwardly from a lower endportion of the oblique wall 228 a. A lower end of the vertical wall 228b is spaced a predetermined distance from the bottom wall 224. A processliquid introduced through the inlet 227 is smoothly guided by the guidewall 228 toward a space 229 enclosed by the outer wall 222, the bottomwall 224, and the inner wall 226.

The middle collecting vessel 240 includes an outer wall 242, a bottomwall 244, an inner wall 246, and a protruded wall 248. The outer wall242, the bottom wall 244, and the inner wall 246 of the middlecollecting vessel 240 have structures similar to those of the outer wall222, the bottom wall 224, and the inner wall 226 of the inner collectingvessel 220. However, since the middle collecting vessel 240 encloses theinner collecting vessel 220, the outer wall 242, the bottom wall 244,and the inner wall 246 of the middle collecting vessel 240 are largerthan the outer wall 222, the bottom wall 224, and the inner wall 226 ofthe inner collecting vessel 220. The outer wall 242 of the middlecollecting vessel 240 includes an oblique wall 242 a. A top end of theoblique wall 242 a is vertically spaced a predetermined distance fromthe top end of the oblique wall 222 a of the outer wall 222 of the innercollecting vessel 220 so as to form the inlet 247 of the middlecollecting vessel 240. The protruded wall 248 extends verticallydownwardly from a lower edge of the bottom wall 244. A top end of theinner wall 246 of the middle collecting vessel 240 extends on to a loweredge of the bottom wall 224 of the inner collecting vessel 220.Slit-shaped exhaust holes 243 are formed in the inner wall 246 of themiddle collecting vessel 240 in a ring fashion for discharging gas. Adischarge pipe 245 is coupled to the bottom wall 244. A used processliquid collected into the middle collecting vessel 240 is discharged toan outer recycle system through the discharge pipe 245.

The outer collecting vessel 260 includes an outer wall 262 and a bottomwall 264. The outer wall 262 of the outer collecting vessel 260 has astructure similar to that of the outer wall 242 of the middle collectingvessel 240. However, since the outer collecting vessel 260 encloses themiddle collecting vessel 240, the outer wall 262 of the outer collectingvessel 260 are larger than the outer wall 242 of the middle collectingvessel 240. The outer wall 262 of the outer collecting vessel 260includes an oblique wall 262 a. A top end of the oblique wall 262 a isvertically spaced a predetermined distance from the top end of theoblique wall 242 a of the outer wall 242 of the middle collecting vessel240 so as to form the inlet 267 of the outer collecting vessel 260. Thebottom wall 264 is shaped like a circular disk and includes an openingfor receiving the rotation shaft 42. A discharge pipe 265 is coupled tothe bottom wall 264. A used process liquid collected into the outercollecting vessel 260 is discharged to an outer recycle system throughthe discharge pipe 265. The outer collecting vessel 260 forms theexterior of the container 20. An exhaust pipe 263 is coupled to thebottom wall 264 of the outer collecting vessel 260. Gas introduced intothe outer collecting vessel 260 is discharged through the exhaust pipe263. In addition, gases discharged through the exhaust holes 223 and 243of the inner walls 226 and 246 of the inner and middle collectingvessels 220 and 240 is discharged to the outside of the container 20through the exhaust pipe 263 connected to the outer collecting vessel260. The exhaust pipe 263 protrudes upward from the bottom wall 264 by apredetermined length.

The lifting unit 30 moves the container 20 straight and vertically. Asthe container 20 moves vertically, the height of the container 20 variesrelative to the height of the spin head 40. The lifting unit 30 includesa bracket 31, a movable shaft 34, and a driving unit 36. The bracket 31is fixed to an outer wall of the container 20, and the movable shaft 34is fixed to the bracket 31. The driving unit 36 moves the movable shaft34 vertically. When a substrate (W) is placed at the spin head 40 orlifted from the spin head 40, the container 20 is moved down so as toexpose the spin head 40 through the top of the container 20. During aprocess, the height of the container 20 is adjusted so that processliquids used to process the substrate (W) can be separately collected tothe collecting vessels 220, 240, and 260. Alternatively, the liftingunit 30 may move the spin head 40 vertically.

An exemplary structure of the spin head 40 will now be described withreference to FIGS. 4 and 5. FIG. 4 is a plan view illustrating the spinhead 40 according to an embodiment of the present invention, and FIG. 5is a sectional view of the spin head 40 taken along line I-I of FIG. 4,according to an embodiment of the present invention. The spin head 40includes a body 300, chuck pins 500, and a chuck pin moving unit 600(refer to FIG. 17).

The chuck pins 500 are installed on an edge portion of the body 300 in amanner such that the chuck pins 500 protrude upward from the top surfaceof the body 300. The number of chuck pins 500 may be about six. Thechuck pins 500 support the edge of a substrate (W) placed at the spinhead 40 so that the substrate (W) can be kept in place without beingdetached from the spin head 40 when the spin head 40 is rotated. Thechuck pins 500 have the same shape and size.

FIG. 6 is a perspective view illustrating the chuck pin 500 according toan embodiment of the present invention. The chuck pin 500 includes avertical rod 520, a support rod 540, a coupling portion 560, and astopper portion 580. When the chuck pin 500 is installed at the body300, the vertical rod 520 may be vertically positioned. The vertical rod520 has a circular cross section perpendicular to its length. When asubstrate (W) placed at the spin head 40 is rotated, the vertical rod520 is spaced apart from the edge of the substrate (W). The support rod540 extends from a side of the vertical rod 520. The support rod 540extends from an end of the vertical rod 520 substantially in ahorizontal direction. A distance between the support rod 540 and thebody 300 is uniform from an end to the other end of the support rod 540.The support rod 540 has substantially the same height as the height of asubstrate (W) placed at the body 300. When the substrate (W) placed atthe body 300 is rotated, the end of the support rod 540 is in contactwith the edge of the substrate (W).

The support rod 540 includes a contact portion 542. The contact portion542 extends to the end of the support rod 540. When viewed from the top,the contact portion 542 is tapered. The contact portion 542 includessymmetric side surfaces 544. The side surfaces 544 of the contactportion 542 are rounded. The side surfaces 544 of the contact portion542 may be streamlined. The contact portion 542 has a width smaller thanthe diameter of the vertical rod 520. The contact portion 542 includes adistal end 546 for making contact with a substrate (W) placed at thebody 300. When viewed from the top, the distal end 546 of the contactportion 542 may look like a point. The contact portion 542 may extenddirectly from the vertical rod 520. Alternatively, as shown in FIG. 7, amiddle portion 543 having a constant width may be provided between thecontact portion 542 and the vertical rod 520.

The coupling portion 560 extends downward from the vertical rod 520. Thecoupling portion 560 includes a screw hole for coupling with the chuckpin moving unit 600. The stopper portion 580 extends outward from thevertical rod 520 and is shaped like a ring. When the chuck pins 500 arecoupled to the body 300, the stoppers 580 of the chuck pins 500 makecontact with a top surface of the body 300 such that the chuck pins 500can have the same protruded height.

FIG. 8 is a view illustrating how the chuck pin 500 supports an edgeportion of a substrate (W) during processing according to an embodimentof the present invention, and FIG. 9 is a plan view illustrating streamsof a process liquid when the spin head 40 rotates according to anembodiment of the present invention. Referring to FIG. 8, the verticalrod 520 having a relatively large cross section is spaced apredetermined distance from the substrate (W). An edge portion of thesubstrate (W) is supported by the contact portion 542, which isrelatively narrower than the vertical rod 520 when viewed from the topand has streamlined side surfaces 544. Therefore, when the substrate (W)is rotated, a process liquid flows to the distal end 546 of the contactportion 542 and then along the side surfaces 544 of the contact portion542. Since the process liquid can flow to a contact region between thesubstrate (W) and the support rod 540, the possibility of occurrence ofprocess defects on the contact region can be reduced.

FIG. 10 is a perspective view illustrating a chuck pin 500′ according toanother embodiment of the present invention. Referring to FIG. 10, thechuck pin 500′ includes a vertical rod 520′, a support rod 540′, acoupling portion 560′, and a stopper portion 580′. The vertical rod520′, the coupling portion 560′, and the stopper portion 580′ of thechuck pin 500′ have substantially the same structures as the verticalrod 520, the coupling portion 560, and the stopper portion 580 of thechuck pin 500 of FIG. 6. Thus, detailed descriptions thereof will beomitted. The support rod 540′ includes a horizontal rod 542′ and acontact rod 544′. The horizontal rod 542′ extends horizontally from thevertical rod 520. The contact rod 544′ protrudes downward from an end ofthe horizontal rod 542′ by a predetermined length. The contact rod 544′extends downward to or below a height where a substrate (W) is placed.During processing, the horizontal rod 542′ is located higher than thesubstrate (W), and the contact rod 544′ is located at a predeterminedheight so that a distal end 546′ of the contact rod 544′ can makecontact with an edge portion of the substrate (W).

When viewed from the top, the contact rod 544′ is gradually tapered awayfrom the vertical rod 520′. The distal end 546′ of the contact rod 544′is viewed as a point when viewed from the top. The contact rod 544′includes side surfaces 544 a′. The side surfaces 544 a′ of the contactrod 544′ are rounded. The side surfaces 544 a′ of the contact rod 544′may be streamlined. The cross-sectional area of the contact rod 544′ isconstant in a length direction of the contact rod 544′. When viewed fromthe top, the width of the contact rod 544′ is smaller than the diameterof the vertical rod 520′. That is, the width of the cross section of thecontact rod 544′ is smaller than the diameter of the cross section ofthe vertical rod 520′.

FIG. 11 illustrates how the contact rod 544′ of FIG. 10 supports an edgeportion of a substrate (W) when the substrate (W) is rotated accordingto an embodiment of the present invention. The vertical rod 520′ isspaced a predetermined distance from the substrate (W), and thehorizontal rod 542′ is located higher than the substrate (W). Therefore,the vertical rod 520′ and the horizontal rod 542′ do not impede streamsgenerated by rotation of the substrate (W). In addition, the contact rod544′ that makes contact with the edge portion of the substrate (W) isnarrow and has the streamlined side surfaces 544 a′. Therefore, whenviewed from the top of the substrate (W), a process liquid can reach thedistal end 546′ of the contact rod 544′. That is, a process liquid canbe supplied to a contact region between the substrate (W) and the chuckpin 500′.

Referring again to FIG. 5, the body 300 includes an upper plate 320, alower plate 340, and pressing parts 360 (refer to FIG. 13). When viewedfrom the top, the upper plate 320 has a circular top surface. The lowerplate 340 is disposed under the upper plate 320 and provides a room forthe chuck pin moving unit 600. Pinholes 322 are formed in an edgeportion of the upper plate 320 for receiving the chuck pins 500. Each ofthe pinholes 322 is shaped like a slit. The pinhole 322 is formed in aradial direction of the upper plate 320. The pin hole 322 has a widthequal to or slightly larger than the diameter of the vertical rod 520 ofthe chuck pin 500. The pinhole 322 has a length in the radial directionof the upper plate 320 for guiding movement of the chuck pin 500 in theradial direction of the upper plate 320. The length of the pinhole 322may be smaller than the diameter of the stopper portion 580 of the chuckpin 500. Alternatively, the pinhole 322 may have a circular shape. Inthis case, the diameter of the pinhole 322 may be greater than thediameter of the vertical rod 520 of the chuck pin 500 but smaller thanthe diameter of the stopper portion 580 of the chuck pin 500.

The lower nozzle member 100 b (refer to FIG. 1) is disposed in the body300. The lower nozzle member 100 b includes an injection portion 182, apassage portion 184, and a gas supply conduit 186. The injection portion182 and the passage portion 184 are disposed in a center region of thebody 300 and are vertically aligned with each other. The passage portion184 is disposed in the center portion of the body 300 and has a constantcross section in its length direction. The passage portion 184 may havea circular cross section. The injection portion 182 extends upward fromthe passage portion 184. A lower end of the injection portion 182 hasthe same cross sectional shape as the cross section shape of the passageportion 184, and the injection portion 182 widens as it goes upward. Forexample, the injection portion 182 may have a reverse conical shape. Thegas supply conduit 186 is connected to a lower end of the passageportion 184 for supplying gas to the passage portion 184. A valve 186 ais installed in the gas supply conduit 186 for opening and closing thegas supply conduit 186 or controlling the amount of gas flowing throughthe gas supply conduit 186.

FIG. 12 is a view illustrating a substrate (W) supported by the body300, streams of a process liquid supplied through the upper nozzlemember 100 a, and streams of gas supplied through the lower nozzlemember 100 b according to an embodiment of the present invention. InFIG. 12, solid-line arrows represent streams of gas supplied through thelower nozzle member 100 b, and dashed-line arrows represent streams of aprocess liquid supplied through the upper nozzle member 100 a. Since gasis supplied through the lower nozzle member 100 b, the substrate (W) canbe stably supported at a predetermined distance apart from the body 300by the pressure of the supplied gas. The entire top surface of thesubstrate (W) is treated by the process liquid supplied from the uppernozzle member 100 a to the top surface of the substrate (W), and only apredetermined edge region of the bottom surface of the substrate (W) istreated by the process liquid supplied from the upper nozzle member 100a since the gas supplied from the lower nozzle member 100 b restrictsflows of the process liquid on the bottom surface of the substrate (W).If the substrate (W) is supported by support pins, flows of the gas maybe disturbed by the support pins. Therefore, the process liquid can flowpast the predetermined edge region of the substrate (W) toward an innerregion of the bottom surface of the substrate (W) through regions aroundthe support pins. However, according to the present invention,structures such as support pins are not disposed between a substrate (W)and the body 300, only a desired region of the bottom surface of thesubstrate (W) can be uniformly treated by a process liquid.

FIGS. 13 and 14 are views for illustrating an exemplary couplingstructure of the upper plate 320 and the lower plate 340. FIG. 13 is asectional view of the spin head 40 taken along line II-II of FIG. 4,according to an embodiment of the present invention, and FIG. 14 is abottom view illustrating the lower plate 340 in the direction of arrow Ain FIG. 13, according to an embodiment of the present invention.Referring to FIGS. 13 and 14, since the upper plate 320 is exposed tochemicals during a process, the upper plate 320 is formed of a materialresistive to chemicals. The lower plate 340 is formed of a heatresistant material so as to prevent the chuck pins 500 from being movedfrom set positions due to thermal deformation of the lower plate 340when a hot chemical is applied to a substrate (W) placed at the spinhead 40. That is, the upper plate 320 is formed of a material havingbetter corrosion resistant characteristics than the lower plate 340, andthe lower plate 340 is formed of a material that is less deformed byheat than the upper plate 320. For example, the upper plate 320 may beformed of polyvinylchloride, and the lower plate 340 may be formed ofaluminum. The upper plate 320 and the lower plate 340 are coupled usingthe pressing parts 360. Threaded grooves 328 are formed in a bottomsurface of the upper plate 320, and slit grooves 342 are formed in thelower plate 340 in radial directions of the body 300 in correspondencewith the threaded grooves 328.

The pressing parts 360 are coupled to the upper plate 320 through theslit grooves 342 in a direction from the lower plate 340 to the upperplate 320. Each of the pressing parts 360 includes a pressing plate 362and a screw 364. A hole 362 c is formed vertically through a centerportion of the pressing plate 362. The screw 364 is inserted through thehole 362 c of the pressing plate 362, the slit groove 342 of the lowerplate 340, and the threaded groove 328 of the upper plate 320 in adirection from the lower plate 340 to the upper plate 320 so as tocouple the upper plate 320 and the lower plate 340. The pressing plate362 includes insertion portion 362 b and a head portion 362 a. Theinsertion portion 362 b is inserted in the slit groove 342 of the lowerplate 340, and the head portion 362 a extends downward from theinsertion portion 362 b for pressing the lower plate 340. The insertionportion 362 b of the pressing plate 362 has a diameter approximatelyequal to the width of the slit groove 342 of the lower plate 340, thehead portion 362 a of the pressing plate 362 has a diameter greater thanthe width of the slit groove 342.

FIG. 15 is a view for explaining advantageous effects when the upperplate 320 and the lower plate 340 are used according to an embodiment ofthe present invention. In FIG. 15, the upper plate 320 is indicated bysolid lines before the upper plate 320 undergoes thermal expansion andis indicated by dashed lines after the upper plate 320 undergoes thermalexpansion. Referring to FIG. 15, although the upper plate 320 expandsdue to a hot chemical, the pressing part 360 is moved independent of thelower plate 340 along the slit groove 342. Therefore, the lower plate340 is not deformed by the thermal expansion of the upper plate 320.Since various components are coupled to the lower plate 340 forpositioning the chuck pins 500, the chuck pins 500 can be prevented frombeing moved from set positions by preventing deformation of the lowerplate 340 as described above.

The chuck pin moving unit 600 moves the chuck pins 500 betweensupporting positions and rest positions. In the supporting positions,the chuck pins 500 are in contact with the edge of a substrate (W)placed at the spin head 40. In the rest positions, the chuck pins 500are located outward from the supporting positions so as to allow asubstrate (W) to be placed at the spin head 40. That is, the supportingpositions are closer to a center portion of the body 300 than the restpositions.

FIG. 16 is a bottom view illustrating the chuck pin moving unit 600according to an embodiment of the present invention, and FIG. 17 is anenlarged view of portion B of FIG. 16, according to an embodiment of thepresent invention. The chuck pin moving unit 600 includes movable rods620, guide members 640, distance adjustors 660, contact maintainingmembers 680, and a linear mover 700.

The number of the movable rods 620 is equal to the number of the chuckpins 500. The moveable rods 620 are coupled to the chuck pins 500,respectively. The movable rods 620 are disposed in the lower plate 340in the radial directions of the body 300. The upper plate 320 includes alateral portion protruded downward from its edge, and holes 329 (referto FIG. 5) are formed through the lateral portion in a direction from anouter surface to an inner surface of the lateral portion. The holes 329communicate with the pinholes 322 of the upper plate 320. An outer endof the movable rod 620 is disposed in the hole 329. A screw hole 628(refer to FIG. 5) is formed in the movable rod 620. The movable rod 620is fixedly coupled to the chuck pin 500 using a screw 590. A sealingmember 330 is disposed in the hole 329 to enclose the movable rod 620for sealing an inner space of the lower plate 340. The sealing member330 may be an o-ring. The movable rod 620 includes a rolling ball 622 atan inner end thereof. The rolling ball 622 is rotatably coupled to theinner end of the movable rod 620.

The guide members 640 are disposed on moving paths of the movable rods620, respectively. The guide members 640 guide linear movements of themovable rods 620 in the radial directions of the body 300. The guidemembers 640 may be sliding bearings fixed to the body 300.

The linear mover 700 moves the movable rods 620 straight in the radialdirections of the body 300 between the rest positions and the supportingpositions. The linear mover 700 includes a cam 720, a cam driving unit730, cam return units 760, and chuck pin return units 780. The cam 720is shaped like a circular ring. The cam 720 includes protrusions 740.The protrusions extend outward from the periphery of the cam 720. Thenumber of the protrusions 740 is equal to the number of the movable rods620, and the protrusions 740 are formed at positions corresponding tothe movable rods 620. Each of the protrusions 740 includes a graduallyinclined front surface 742 and a steeply inclined rear surface 744. Thecam driving unit 730 rotates the cam 720 in a first rotation direction82, and the cam return units 760 rotate the cam 720 in a second rotationdirection 84 opposite to the first rotation direction 82. A rotarycylinder may be used as the cam driving unit 730 for rotating the cam720 a predetermined angle. The rotary cylinder may rotate a rotationshaft (not shown) fixed to the cam 720. Cam stoppers 750 are fixed tothe body 300 beside the protrusions 740 for restricting rotation of thecam 720. The cam return units 760 may include springs 762 providingelastic forces for returning the cam 720. Ends of the spring 762 arefixed to first hooks 764 of the cam 720, and the other ends of thesprings 762 are fixed to second hooks 766 of the lower plate 340. Thefirst hooks 764 are closer to the protrusions 740 than the second hooks766.

In an embodiment, the cam driving unit 730 may rotate the cam 720 sothat the rolling ball 622 can rotate upward on the front surface 742 ofthe protrusion 740. As the cam 720 is rotated in the first rotationdirection 82, the chuck pin 500 is moved from the supporting position tothe rest position, and the spring 762 of the cam return unit 760extends. If a driving force of the cam driving unit 730 is interrupted,the cam 720 is rotated in the second rotation direction 84 by aresilient force of the spring 762, and the rolling ball 622 is movedaway from the front surface 742 of the protrusion 740. In the currentembodiment, when the chuck pin 500 is in the supporting position, thespring 762 is in equilibrium. Therefore, although the cam driving unit730 malfunctions, a substrate (W) can be stably supported by the chuckpin 500.

In another embodiment, the cam 720 can be returned to its originalposition using a magnetic force. For this, as shown in FIG. 18, a firstmagnet 762 a is disposed at the cam 720, and the second magnet 762 b isdisposed at the body 300. The first and second magnets 762 a and 762 bare arranged such that when a driving force applied to the cam 720 isinterrupted, the chuck pin 500 can be moved from the rest position tothe supporting position. For example, the first magnet 762 a may bedisposed between the protrusion 740 and the second magnet 762 b. Thefirst and second magnets 762 a and 762 b may be oriented so thatopposite poles of the first and second magnets 762 a and 762 b can faceeach other.

In another embodiment, the cam driving unit 730 may rotate the cam 720to move the chuck pin 500 from the rest position to the supportingposition, and the cam return units 760 may rotate the cam 720 to movethe chuck pin 500 from the supporting position to the rest position.

In another embodiment, the chuck pin 500 may be moved by the cam drivingunit 730 in both directions from the rest position to the supportingposition and from the supporting position to the rest position.

As explained above, when the cam 720 is rotated in the first rotationdirection 82, the rolling ball 622 rotates along the front surface 742of the protrusion 740 away from the cam 720. When the cam 720 is rotatedin the second rotation direction 84, the chuck pin return units 780moves the chuck pin 500 from the rest position to the supportingposition using a resilient force. In the embodiment shown in FIG. 17,the chuck pin return unit 780 includes an elastic member such as aspring 782 for returning the chuck pin 500 using the elastic force ofthe spring 782. An end of the spring 782 is fixed to a first hook 784extending from an end portion of the movable rod 620, and the other endof the spring 782 is fixed to a second hook 786 fixedly coupled to thebody 300. The second hook 786 is disposed between the first hook 784 andthe cam 720. Thus, when the movable rod 620 is moved away from the cam720, the spring 782 is extended. When the cam 720 is rotated in thesecond rotation direction 84 by a resilient force, the movable rod 620is moved toward the cam 720 by an elastic force of the spring 782, andthus the chuck pin 500 is moved from the rest position to the supportingposition.

In another embodiment shown in FIG. 19, the chuck pin 500 may bereturned from the rest position to the supporting position by a magneticforce. For example, a first magnet 782 a may be disposed at the movablerod 620, and a second magnet 782 b may be disposed at the body 300. Thepoles of the first and second magnets 782 a and 782 b are matched suchthat the chuck pin 500 can be moved from the rest position to thesupporting position by the magnetic force of the first and secondmagnets 782 a and 782 b when a driving force of the cam driving unit 730is interrupted. When the second magnet 782 b is closer to the center ofthe body 300 than the first magnet 782 a as shown in FIG. 19, the firstand second magnets 782 a and 782 b are oriented with opposite poles ofthe first and second magnets 782 a and 782 b facing each other. On theother hand, when the first magnet 782 a is closer to the center of thebody 300 than the second magnet 782 b, the first and second magnets 782a and 782 b are oriented with like poles of the first and second magnets782 a and 782 b facing each other.

If the movable rods 620 are moved toward the center of the body 300 by asingle force, the chuck pins 500 may not be individually moved. In thiscase, although the chuck pins 500 are moved to the supporting positions,some of the chuck pins 500 may not be in contact with the edge of asubstrate (W) placed at the spin head 40 due to machining errors ofcomponents such as the chuck pins 500, the movable rods 620, and the cam720. Therefore, when the spin head 40 is rotated, stresses may beconcentrated on some of the chuck pins 500 that make contact with theedge of the substrate (W). Thus, the chuck pins 500 can be easilydamaged and broken. However, in the present invention, since the chuckpin return units 780 are respectively disposed at the movable rods 620,the movable rods 620 can be moved toward the center of the body 300 byreturning forces individually applied to the movable rod 620. Therefore,although components such as the chuck pins 500, the movable rods 620,and the cam 720 are not uniform in size due to machining errors, all thechuck pins 500 can be in contact with the edge of a substrate (W) whenthe chuck pins 500 are moved to the supporting positions.

FIGS. 20A and 20B are views for explaining an exemplary relationshipamong the rotation direction of the cam 720, operations of the camreturn unit 760 and the chuck pin return unit 780, and the movingdirection of the movable rod 620 according to an embodiment of thepresent invention. Referring to FIG. 20A, when the cam 720 is rotated bythe cam driving unit 730 in the first rotation direction 82, the spring762 of the cam return unit 760 is extended, and the movable rod 620 ismoved from the supporting position to the rest position. Thus, thespring 782 of the chuck pin return unit 780 is extended. Then, when adriving force of the cam driving unit 730 is interrupted as shown inFIG. 20B, the cam 720 is rotated in the second rotation direction 84 byan elastic force of the cam return unit 760, and the movable rod 620 ismoved from the rest position to the supporting position by an elasticforce of the chuck pin return unit 780.

In the above-described embodiments, the chuck pins 500 are switchedbetween the supporting positions and the rest positions by moving thechuck pins 500 straight in radial directions of the body 300. However,alternatively, the support rods 540 of the chuck pins 500 may beswitched between rest positions and supporting positions by rotating thevertical rods 520 of the chuck pins 500 using the chuck pin moving unit600.

If the spin head 40 is rotated at high speed, the chuck pins 500 can bemoved outward in radial directions of the body 300 by a centrifugalforce. In this case, a substrate (W) placed at the spin head 46 may beunstably supported by the chuck pins 500. To prevent this situation, thecontact maintaining member 680 holds the chuck pin 500 at the supportingposition to maintain contact between the chuck pin 500 and the edge ofthe substrate (W) when the spin head 40 is rotated. The contactmaintaining member 680 includes a fixed pin 680 a and a maintaining bar680 b. The fixed pin 680 a is fixed to the movable rod 620 and isprotruded from the movable rod 620. When the spin head 40 is rotated,the maintaining bar 680 b pushes the fixed pin 680 a toward the centerof the body 300.

For example, the maintaining bar 680 b may be configured to push thefixed pin 680 a using a centrifugal force when the spin head 40 isrotated. Referring to FIG. 16, the maintaining bar 680 b includes acenter portion 682, a pressing portion 684, and a guide portion 686. Thecenter portion 682 is coupled to the body 300 using a pin 681 and isrotatable with respect to the body 300. The pressing portion 684 pushesthe fixed pin 680 a toward the center of the body 300 when the spin head40 is rotated. The guide portion 686 causes the pressing portion 684 tomove toward the fixed pin 680 a when the spin head 40 is rotated. Thepressing portion 684 extends from the center portion 682 in apredetermined direction, and the guide portion 686 extends from thecenter portion 682 at an obtuse angle with the pressing portion 684. Thepressing portion 684 and the guide portion 686 are shaped like a rod.

When the spin head 40 rotates, the guide portion 686 receives acentrifugal force greater than a centrifugal force acting on thepressing portion 684. The guide portion 686 is heavier than the pressingportion 684. When viewed from the top, the guide portion 686 may bewider than the pressing portion 684. A free end of the guide portion 686may be wider than the pressing portion 684.

The contact maintaining member 680 is oriented such that the pressingportion 684 is directed to the movable rod 620 and the guide portion 686is disposed away from the movable rod 620. The pressing portion 684 isdisposed opposite to the cam 720 with respect to the fixed pin 680 a.The distance between the guide portion 686 and the movable rod 620increases in a direction away from the center of the body 300.

FIG. 21 illustrates an exemplary operation of the contact maintainingmember 680 according to an embodiment of the present invention. When thespin head 40 does not rotate, no force is applied to the pressingportion 684. When the movable rod 620 is moved away from the center ofthe body 300 by rotation of the cam 720, the fixed pin 680 a pushes thepressing portion 684 in a direction away from the center of the body300, and thus the pressing portion 684 is rotated not to impede themovement of the movable rod 620. Here, the guide portion 686 is notrotated more than a predetermined angle owing to a stopper 687 fixed tothe body 300 at a position opposite to the movable rod 620 with respectto the guide portion 686. When the chuck pin 500 is in the supportingposition and the spin head 40 is rotated, the guide portion 686 isrotated toward the movable rod 620 since a centrifugal force is appliedto the guide portion 686. Since the pressing portion 684 is fixed to theguide portion 686, the pressing portion 684 rotated with the guideportion 686. That is, the pressing portion 684 is rotated toward thefixed pin 680 a in a direction opposite to the direction of thecentrifugal force. Thus, the fixed pin 680 a can be pushed by thepressing portion 684 toward the center of the body 300. Therefore, whilethe spin head 40 is rotated, the chuck pin 500 can be kept in contactwith the edge of a substrate (W) placed at the spin head 40.

Since the fixed pin 680 a of the contact maintaining member 680 ispushed toward the center of the body 300 using a centrifugal force whenthe spin head 40 is rotated, an additional driving unit is unnecessaryfor driving the contact maintaining member 680, and thus the contactmaintaining member 680 can have a simple structure. Alternatively, anadditional driving unit can be used to rotate the contact maintainingmember 680 so as to push the movable rod 620 toward the center of thebody 300 when the spin head 40 is rotated.

The diameter of a substrate (W) can be varied due to the previousprocess. For example, if the substrate (W) is heat treated in theprevious process, the diameter of the substrate (W) may be varied due tothermal expansion. For this, the distance adjustor 660 can be used toadjust the supporting position of the chuck pin 500. The distanceadjustor 660 includes an adjustment block 662 and fixing members 664.The adjustment block 662 includes a slit shaped penetration hole. Thelength of the penetration hole is parallel with the moving direction ofthe movable rod 620. The fixing members 664 are used to fix theadjustment block 662 to the body 300. Each of the fixing members 664includes a head portion 664 a and an insertion portion 664 b extendingfrom the head portion 664 a. The head portion 664 a is greater than thewidth of the penetration hole. The insertion portion 664 b is insertedthrough the penetration hole and is coupled to a screw groove (notshown) formed in the body 300. The head portion 664 a can be pressedagainst the adjustment block 662 by inserting the insertion portion 664b into the body 300. In this way, the adjustment block 662 can be fixedto the body 300. The number of the fixing members 664 may be two. Astopper 666 is disposed at the movable rod 620. The adjustment block 662is disposed between the stopper 666 and the cam 720. When the movablerod 620 is moved toward the center of the body 300 by a resilient forceof the chuck pin return unit 780, the stopper 666 makes contact with anend of the adjustment block 662 so that the movement of the movable rod620 can be restricted.

The supporting position of the chuck pin 500 can be adjusted as follows.First, the fixing member 664 is unfastened to remove a pressing forceapplied to the adjustment block 662 by the head portion 664 a of thefixing member 664. Next, the adjustment block 662 is moved to a desiredposition. If the adjustment block 662 is moved away from the center ofthe body 300 in a radial direction of the body 300, the supportingposition of the chuck pin 500 is also moved away from the center of thebody 300. On the other hand, if the adjustment block 662 is moved towardthe center of the body 300 in the radial direction of the body 300, thesupporting position of the chuck pin 500 is also moved toward the centerof the body 300. Then, the fixing member 664 is fastened to fix theadjustment block 662 to the body 300. FIG. 22 is a view illustrating howthe supporting position of the chuck pin 500 is changed by moving theadjustment block 662 according to an embodiment of the presentinvention. In FIG. 22, components are indicated by solid lines beforethe adjustment block 662 is moved. After the adjustment block 662 ismoved, moved components are indicated by dashed lines.

According to the present invention, although the chuck pins are incontact with the edge of a substrate for supporting the substrate, aprocess liquid can be smoothly supplied to contact regions between thechuck pins and the substrate so that the substrate can be uniformlytreated.

Furthermore, according to the present invention, a bottom edge region ofa substrate can be uniformly treated using a process liquid that isdirected to the bottom surface of the substrate after being used totreat the top surface of the substrate.

Moreover, according to the present invention, when a substrate issupported by the chuck pins, all the chuck pins can stably make contactwith the edge of the substrate. Therefore, the substrate can be stablysupported, and stress concentration on some of the chuck pins can beprevented.

In addition, according to the present invention, even when a substrateis rotated at high speed, the chuck pins can be stably held in thesupporting positions and make contact with the edge of the substrate.

The above-disclosed subject matter is to be considered illustrative, andnot restrictive, and the appended claims are intended to cover all suchmodifications, enhancements, and other embodiments, which fall withinthe true spirit and scope of the present invention. Thus, to the maximumextent allowed by law, the scope of the present invention is to bedetermined by the broadest permissible interpretation of the followingclaims and their equivalents, and shall not be restricted or limited bythe foregoing detailed description.

1. A spin head for supporting a substrate, comprising: a rotatable body;and chuck pins protruding upward from the body and configured to supportan edge of a substrate placed at the body when the body is rotated,wherein each of the chuck pins comprises: a vertical rod verticallydisposed at the body; and a support rod extending from a side of thevertical rod and configured to make contact with the edge of thesubstrate placed at the body when the body is rotated.
 2. The spin headof claim 1, wherein the support rod comprises a contact portionextending to an end of the support rod, the contact portion taperingtoward the end of the support rod when viewed from a top of the supportrod.
 3. The spin head of claim 2, wherein the contact portion comprisesa rounded side surface in a length direction of the support rod.
 4. Thespin head of claim 2, wherein the contact portion comprises astreamlined side surface in a length direction of the support rod. 5.The spin head of claim 2, wherein the support rod has a uniform heightfrom a top surface of the body in a length direction of the support rod.6. The spin head of claim 1, wherein the support rod tapers from theside of the vertical rod to an end thereof when viewed from a top of thesupport rod.
 7. The spin head of claim 2, wherein the support rodcomprises a distal end that is viewed as a point when viewed from thetop of the support rod.
 8. The spin head of claim 1, wherein the supportrod comprises: a horizontal rod extending laterally from the verticalrod; and a contact rod bent downward from an end of the horizontal rod.9. The spin head of claim 8, wherein the contact rod has the same crosssection along a length of the contact rod.
 10. The spin head of claim 8,wherein the contact rod tapers away from the vertical rod.
 11. The spinhead of claim 8, wherein the contact rod comprises a streamlined sidesurface.
 12. The spin head of claim 10, wherein the vertical rod has acircular section, and the contact rod has a width smaller than adiameter of the circular section of the vertical rod when viewed from atop of the contact rod.
 13. The spin head of claim 1, further comprisinga chuck pin moving unit configured to move the chuck pins in radialdirections of the body, wherein the chuck pin moving unit comprises:movable rods fixed to the chuck pins; a rotatable cam comprisingprotrusions on an outer surface thereof so as to move the chuck pinsaway from a center of the body; and chuck pin return units applyingforces to the movable rods, respectively, so as to individually move thechuck pins toward the center of the body.
 14. The spin head of claim 13,wherein the chuck pin moving unit further comprises contact maintainingmembers, the contact maintaining members being configured to push thechuck pins toward the center of the body when the body is rotated so asto prevent the chuck pins from moving away from the center of the bodyby a centrifugal force.
 15. The spin head of claim 1, wherein the bodycomprises a lower nozzle member through which gas is injected so as tospace the substrate apart from the body.
 16. The spin head of claim 15,wherein the lower nozzle member comprises an injection hole formed in atop surface of the body into a circular shape.
 17. The spin head ofclaim 16, wherein the lower nozzle member further comprises: a passageportion connected to a gas supply conduit and having the same crosssection along a length thereof; and an injection portion extendingupward from the passage portion and connected to the injection hole, theinjection portion having a gradually increasing cross section along anupward direction.
 18. A chuck pin used in a rotatable spin head forsupporting an edge of a substrate, the chuck pin comprising: a verticalrod disposed in a vertical direction; and a support rod extending from aside of the vertical rod.
 19. The chuck pin of claim 18, wherein thesupport rod comprises a contact portion extending to an end of thesupport rod, the contact portion tapering toward the end of the supportrod.
 20. The chuck pin of claim 19, wherein the contact portioncomprises a rounded side surface in a length direction of the supportrod.
 21. The chuck pin of claim 19, wherein the contact portioncomprises a streamlined side surface.
 22. The chuck pin of claim 19,wherein the support rod has a uniform height in a length directionthereof.
 23. The chuck pin of claim 18, wherein the support rodcomprises: a horizontal rod extending laterally from the vertical rod;and a contact rod bent downward from an end of the horizontal rod. 24.The chuck pin of claim 23, wherein the contact rod tapers away from thevertical rod.
 25. The chuck pin of claim 24, wherein the contact rod hasthe same cross section along a length of the contact rod.
 26. The chuckpin of claim 24, wherein the contact rod comprises a streamlined sidesurface.
 27. A method for treating a substrate, the method comprisingsupporting a substrate placed at a body of a spin head by brining chuckpins into contact with an edge of the substrate, wherein each of thechuck pins comprises a vertical rod vertically disposed at the body anda support rod extending from a side of the vertical rod, wherein whenthe chuck pin supports the substrate, the vertical rod is spaced apartfrom the substrate in a lateral direction, and a distal end of thesupport rod is brought into contact with the edge of the substrate. 28.The method of claim 27, wherein the support rod comprises a contactportion extending to an end of the support rod in a tapered shape whenviewed from a top of the support rod, and the contact portion ishorizontally disposed at the same height as the substrate placed at thespin head.
 29. The method of claim 27, wherein the support rodcomprises: a horizontal rod extending laterally from the vertical rod;and a contact rod bent downward from an end of the horizontal rod,wherein the horizontal rod is horizontally disposed higher than thesubstrate placed at the spin head, and the contact rod extends downwardto a level of the substrate placed at the spin head or lower than thelevel of the substrate placed at the spin head.
 30. The method of claim29, wherein the contact rod tapers away from the vertical rod whenviewed form a top of the contact rod.
 31. The method of claim 30,wherein the contact rod has the same cross section along a lengththereof.
 32. The method of claim 27, wherein the substrate is placed atthe spin head with a patterned side of the substrate facing downward,and a process liquid is supplied to a top center portion of thesubstrate when the spin head is rotated.
 33. The method of claim 32,wherein the substrate is spaced a predetermined distance from the spinhead by a pressure of gas injected upward from the spin head.